Oxsoralen-Ultra

SIDE EFFECTS

Methoxsalen

The most commonly reported side effect of methoxsalen alone is nausea, which occurs with approximately 10% of all patients. This effect may be minimized or avoided by instructing the patient to take methoxsalen in milk or food, or to divide the dose into two portions, taken approximately one-half hour apart. Other effects include nervousness, insomnia, and depression.

Combined Methoxsalen/UVA Therapy:

PRURITUS: This adverse reaction occurs with approximately 10% of
all patients. In most cases, pruritus can be alleviated with frequent application
of bland emollients or other topical agents; severe pruritus may require systemic
treatment. If pruritus is unresponsive to these measures, shield pruritic
areas from further UVA exposure until the condition resolves. If intractable
pruritus is generalized, UVA treatment should be discontinued until the pruritus
disappears.

ERYTHEMA: Mild, transient erythema at 24-48 hours after PUVA therapy
is an expected reaction and indicates that a therapeutic interaction between
methoxsalen and UVA occurred. Any area showing moderate erythema (greater
than Grade 2 -See Table 1 for grades of erythema)
should be shielded during subsequent UVA exposures until the erythema has
resolved. Erythema greater than Grade 2 which appears within 24 hours after
UVA treatment may signal a potentially severe burn. Erythema may become progressively
worse over the next 24 hours, since the peak erythemal reaction characteristically
occurs 48 hours or later after methoxsalen ingestion. The patient should be
protected from further UVA exposures and sunlight, and should be monitored
closely.

IMPORTANT DIFFERENCES BETWEEN PUVA ERYTHEMA AND SUNBURN: PUVA-induced
inflammation differs from sunburn or UVB phototherapy in several ways. The
percent transmission of UVB varies between 0% to 34% through skin whereas
UVA varies between 1% to 80% transmission; thus, UVA is transmitted to a larger
percent through the skin. (Diffey, 198222). The DNA lesions induced
by PUVA are very different from UV-induced thymine dimers and may lead to
a DNA crosslink. This DNA lesion may be more problematic to the cell because
crosslinks are more lethal and psoralen-DNA photoproducts may be "new"
or unfamiliar substrates for DNA repair enzymes. DNA synthesis is also suppressed
longer after PUVA. The time course of delayed erythema is different with PUVA
and may not involve the usual mediators seen in sunburn. PUVA-induced redness
may be just beginning at 24 hours, when UVB erythema has already passed its
peak. The erythema dose-response curve is also steeper for PUVA. Compared
to equally erythemogenic doses of UVB, the histologic alterations induced
by PUVA show more dermal vessel damage and longer duration of epidermal and
dermal abnormalities.